Hydrocarbon conversion over activated erionite

ABSTRACT

This invention is directed to the shape selective conversion of a hydrocarbon charge over H-erionite, both natural and synthetic, which has been activated by exchanging with the ammonium ion as a first step, calcining in steam and exchanging with the ammonium ion. The conversion is conducted in the presence of a hydrogen atmosphere but in the absence of any hydrogenating catalyst such as a metal of the platinum group.

United States Patent [191 Burgess Dec. 9, 1975 [75] Inventor: William P. Burgess, Hopewell, NJ.

[73] Assignee: Mobil Oil Corporation, New York,

[22] Filed: July 17, 1974 [21] Appl. No.: 489,952

[52] US. Cl. 208/111; 208/DIG. 2; 208/66;

[51] Int. Cl. ..C10G 13/04; ClOG 37/06;

[58] Field of Search 208/111, 120

[56] References Cited UNITED STATES PATENTS 2,950,952 8/1960 Breck et a1. 423/329 3,287,252 11/1966 Young 208/59 3,379,640 4/1968 Chen et a1. 208/111 3,474,025 10/1969 Garwood 208/111 3,535,225 10/1970 Jaffe 208/59 3,575,846 4/1971 Hamner et al. 208/111 3,591,488 7/1971 Eberly et. a1. 208/111 3,598,719 8/1971 White 208/59 3,644,200 2/1972 Young 208/120 3,783,123 l/1974 Young 208/111 3,783,124 l/l974 Rubin et al. 208/111 Primary ExaminerDe1bert E. Gantz Assistant Examiner-G. E. Schmitkons Attorney, Agent, or Firm-Charles A. Huggett;

Raymond W. Barclay; Claude E. Setliff [57] ABSTRACT This invention is directed to the shape selective conversion of a hydrocarbon charge over H-erionite, both natural and synthetic, which has been activated by exchanging with the ammonium ion as a first step, calcining in steam and exchanging with the ammonium ion. The conversion is conducted in the presence of a hydrogen atmosphere but in the absence of any hydrogenating catalyst such as a metal of the platinum group.

8 Claims, 2 Drawing Figures EFFECT of DH O on ACTIVATION 0f ERIONITE O 20 4O 6O Time on Stream (min) O 100% Steam X 355 mm 0 25mm CI 0mm US. Patent Dec. 9, 1975 3,925,191

FIGURE 1. EFFECT of pi I20 0|. ACTIVATION of ERIONITE 100 Steam 8 X 355mm 7 0 25mm s El 0mm x0 5 \a Cl) m 4 x x 0.1 O 20 4O 6O 80 I00 I20 Time on Sfreom(min) FIGURE 2.

Method 1 L0 Methods 2ond3 7 J, .6 E s C E 4 Q 3 g 2 I-v HYDROCARBON CONVERSION OVER ACTIVATED ERIONITE BACKGROUND OF THE INVENTION 1. Field of the Invention The invention is concerned with hydrocarbon conversion processes. More particularly it is concerned with the shape selective conversion of a hydrocarbon charge by contacting same with specially treated H- erionite in the presence of hydrogen but in the absence of a hydrogenation catalyst.

2. Discussion of the Prior Art It is well known in the prior art to crack a hydrocarbon charge by contacting it with a zeolite to which a hydrogenation catalyst has been added, either by impregnation or by ion exchange. For example, US. Pat. No. 3,379,640 relates generally to a shape selective hydrocarbon conversion process in which the zeolite must meet three critical criteria. These are that, first, it must have a certain silicon to aluminum ratio, second, there must be no hydrogenation/dehydrogenation metals, etc. on the surface of the crystal and third, any hydrogenation/dehydrogenation component present therein must be within the interior of the crystal and be present to no greater extent than about 1.5 cations in a supercage of metals having hydrogenation/dehydrogenation activity.

US. Pat. No. 3,575,846 is concerned with a selective hydrocracking process accomplished in the presence of an erionite catalyst having a low potassium content and combined with a metallic hydrogenation component.

US. Pat. No. 3,474,025 discloses the use of a zeolite in shape selective hydrocarbon conversions, the zeolite containing no hydrogenating catalyst. The patent discloses the zeolite to be offretite, but it is now known that the zeolite described in such patent is actually erionite. In any event, the present invention is distinguishable over US. Pat. No. 3,474,025 in at least two respects. First, the zeolite of the above patent must have inserted therein a certain amount of rare earth cations and second, the activation procedure, as exemplified in Experiment 3, column 2, lacks the preheating and the second NHfexchange, which contributes to the catalysts of the present invention having such high activities.

SUMMARY OF THE INVENTION In accordance with the present invention there is provided a method for the shape selective conversion of a straight chain hydrocarbon in hydrocarbon mixtures containing same by contacting the hydrocarbon with a crystalline aluminosilicate erionite which has been activated by a procedure comprising the steps of exchanging with the ammonium cation, heating in steam at from about 700F to about l400F and exchanging again with the ammonium cation. The conversion is carried out at from about 500F to about 1000F, in the presence of hydrogen, but in the absence of hydrogenation-dehydrogenation catalytic metal components.

DESCRIPTION OF'SPECIFIC EMBODIMENTS Erionite per se is a naturally occurring zeolite having elliptical pore openings of about 4.7 to 5.2 angstroms on its major axis. Synthetic erionite, called Zeolite T in the art, is described in US. Pat. No. 2,950,952. It is characterized in such patent as having the following mole ratios of oxides:

1.1 x 0.4 [xNa O:( l-x)K O]:Al O :6.9 i 0.5 SiO where x is from about 0.1 to about 0.8 and y is about 0 to about 8.

The ability of erionite to selectively catalyze the conversion of straight-chain hydrocarbons in a hydrocarbon charge is surprisingly improved by following the treatment procedure described herein. Conventional means for exchanging the Na and/or K cations in erionite include an exchange (which generally involves a series of exchanges) with a cation, such as the NI-I cation, followed by a heating step to activate the zeolite. As is evident from U.S. Pat. No; 3,474,025, column 2 (Experiment 3), such procedure produces H-erionite with low K and Na contents, but with very low activity.

In carrying out the process of this invention, the zeolite is first exchanged with a salt solution of the NHfcation, the concentration of the salt not being critical. Any of the soluble salts of the NI-Ifcation may be used. These include the inorganic sulfate or nitrate salts as well as the organic acetateor formate salts. The exchange is carried out by mixing an excess of the salt solution with the zeolites and maintaining contact therewith for from about 10 minutes to about 30 hours.

The rate of exchange can be increased by carrying it out at an elevated temperature. Obviously, the exchange temperature of the solution must be below the atmosphere boiling point of the solution. It may of course be higher than one atmosphere and may range from about one atmosphere to about 3000 psig, when pressure equipment is used. Suitable exchange may be carried out at temperatures of from about F to about 68031 The excess salts are removed usually by washing.

Following this exchange procedure the exchanged erionite is heated in l00% steam at from about 700F to about 1400F, preferably about 950F to about 1250F. The temperature must not be so high, though, that it will cause the zeolite crystalline structure to collapse. The treatment time will depend upon the temperature employed with suitable results being obtained at a temperature of 1000F to l200F for periods of from about 1 /2 to 2 hours.

In the next step the exchanged and steamed zeolite is again exchanged with ammonium cations as before. After washing and drying, the finally exchanged erionite is activated by calcining at from about 750F to about l000F for from about 2 to about 20 hours.

The following examples will illustrate the invention.

Example 1 This example illustrates the effects on precalcination of varying amounts of water in the heating atmosphere. Erionite ore (C, 3, 4, 5 ore) was exchanged twice for 16 hours and 4 hours, respectively, with 5M NII CI at reflux temperature. The residual potassium content was 2.6%. Portions of the sample were calcined with various air/water mixtures at 1 atm. for 1 /2 hours at 1000F, at 0, 25, 355 and 760 mm partial pressure of water in the air. Each sample was then exchanged with 4M (NI-I SO once for 16 hours.

These catalysts were calcined for 2 hours in dry air at l000F and analyzed. They were then tested in the hexane conversion test, or the so-called shape selective alpha test, using the continuous mode, with a 3-component feed (normal hexane, 3-methylpentane and 2,3- dimethylbutane) at 750F. In general, the feed is charged over the catalyst and the product is analyzed at 3 regular intervals.

The effect on activity of the water partial pressure in the precalcination step is shown in FIG. 1 in which the n-hexane first order cracking rate constant (k, we) vs. time on steam (TOS) is plotted. The plot shows very little differences in activity due to the effect of various water concentrations in the precalcination air at less than 355 mm Hg of water. It is significant, however, that at 1 atm. of water (i.e. 100% water) the treated zeolite has significantly higher activity on the order of twice that of catalysts prepared using less water in the calcining atmosphere.

EXAMPLE 2 This example compares the activity of steamed erionite with erionite that has been calcined in air or exchanged in an autoclave. In preparing the samples, the following was done.

1. Ammonium erionite samples were steamed at 1000F for 1.5 hours and 1 atm. of water, and were then exchanged again with the ammonium ion, washed and heated at 1000F for 2 hours.

2. Same as 1. except calcining was in dry air.

3. Ammonium erionite samples were placed in an autoclave with 4M (1 IH SO and maintained for 16 hours at various temperatures and pressures. After autoclaving, samples were water washed and heated at lOF for 2 hours.

The erionite was the erionite ore of Example 1 and the exchanges were substantially as described in that example.

The potassium contents of the various samples are The acid cracking activity of these samples was measured in the alpha test. The lO-minute activity (first order cracking rate constant for n-hexane cracking after minutes on stream) is plotted as a function of K level in the samples in FIG. 2. Samples prepared by method 1 form one curve; those prepared by methods 2 and 3 form the other. It may be seen that steaming produced a more active catalyst.

EXAMPLE 3 This example shows the stability of steamed ammonium erionite in the conversion of a C -260F reformate having the following properties.

Octane No. 76.0 (R+O) Density 0.7365 g/cc Paraffins, wt. 59.3 Naphthenes 3.1 Aromatics 37.6

-continued Wt. normal paraffins s 9.07 C-, 5.72 Cg 1.48

C3.4.5 erionite ore was exchanged with refluxing 5N NH.,C1( 13 ml/grams of zeolite) for 16 hours, was washed, reexchanged (under the same conditions) for 4 hours and washed free of excess Cl ion. The ammonium form of the ore was then steamed at 1000F and 1 atmosphere of H 0 for 1 hour. The steamed zeolite was then exchanged with excess refluxing 8N (NI-1 SO for 16 hours and was finally washed until all excess NH and S0 ions were removed.

The catalyst was tested for its activity in converting n-C and n-C hydrocarbons out of a reformate (defined hereinabove). The test was run at 250 psig, 3 LHSV (3.9 Wl-ISV) and at a 5/1 hydrogen/hydrocarbon ratio. The catalyst contained no nickel or other hydrogenation/dehydrogenation component.

Table 2 summarizes the data obtained at three different temperatures. The last point on the graph (at 78 days) was obtained following regeneration at 900F.

Comparable results with air-calcined ammonium erionite shows that the activity of such catalyst levels off at a point below those obtained with commercial catalysts containing erionite and a hydrogenation-dehydrogenation component.

TABLE 2 *After regeneration at 900F EXAMPLE 4 a. A sample of Zeolite T (synthetic erionite) was given two 16 hour exchanges with 4 molar (NH SO This was washed and dried.

b. (a) was steamed (100% H O) at 1000F for 1 /2 hours then exchanged once with (NI-10 80 under the conditions described above.

0. (b) was steamed H O) at 1000F for 1 /2 hours then exchanged once with (NI-1 350 as above. All exchanges in this and the above examples were at reflux.

Catalysts (a), (b) and (c) were used in the conversion of a C -290F reformate (as defined in Example 3). The results are reported in Table 3.

TABLE 3 Catalyst Example 4(a) Example 4(b) 7 Example 4(c) LHSV (hr) 8.8 9.0 9.0 9.2 9.1 8.8 9.0 9.0 9.0 9.0 9.1 9.1 9.0 9.1 Pressure (psig) 250 250 250 H lHC (mole/mole) 5.3 5.2 i 5.3 Time on Stream (hrs.) 6 24 48 54 78 6 24 52 75 6 24 48 54- 77 Temperature (F) 850 850 850 900 850 850 850 900 850 850 850 850 900 850 -Wt.% Hydrocarbon Product C 0.2 0.2 0.2 0.6 0.2 0.3 0.4 1.3 0.8 0.3 0.4 0.5 .13 0.6 C 0.3 0.4 0.4 1.1 0.4 0.6 0.8 2.1 1.2 0.6 0.8 1.0 2.1 1.0 C; .43 4.0 4.7 8.2 5.0 2.4 9.7 12.6 14.5 6.7 9.9 9.8 12.4 11.2 i-C. 0.5 0.2 0.2 0.4 10.3 0.5 0.4 0.2 0.3 0.4 0.3 0.2 0.2 0.3 n C, 1.0 0.9 0.9 1.5 1.0 1.4 1.4 1.3 0.8 1.3 1.6 1.4 1.3 1.5. C,+ 93.8 94.4 93.6 88.3 93.1 88.8 87.4 82.6 82.4 90.9 87.0 87.1 82.8 85.4

Conversions I n-C, 40 41 46 71 47 67 77 98 81 62 73 84 98 92 n C, 36 37 42 72 44 64 76 99 93 58 71 84 99 92 n-C, 25 27 61 29 47 60 97 88 .52 97 87 c; Octane, 82.0 82.0 82.6 84.7 82.6 85.3 86.2 90.4 89.0 86:4 87.5 85.9 89. 88.2 Calculated R+O(5l -continued The importance of the invention described herein Generally Particularly can be appreciated when it is realized that heretofore, 25 preferred preferred when a crystalline aluminosilicate was used in a selec- Hydrogen rate, Scf/b 50-10,000 1000-4000 tive cracking or hydrocracking operation, it was necessary to have associated therewith a hydrogenationdehydrogenation component, either as an elemental metal or in the form of a metallic cation. This is apparent from two of the three patents discussed hereinabove in the section on prior art.

The feed stocks utilized in the present invention will generally include mixtures of hydrocarbons and particularly petroleum distillates falling within the approximate range of about 80 to about 750F., which range will include naphthas, gaoslines, kerosenes, gas oils, middle distillates, and the like. Preferably, the feed will be predominantly naptha-containing and may consist of either low boiling or high boiling naphthas. Typical low boiling feeds will have boiling ranges of about 50 to 250F., preferably 75 to 180F., whereas typical heavy naphtha feeds will boil within the range of about 350 to 450F., preferably 375 to 430F. Examples of such feed stocks, both low boiling and high boiling, are virgin naphtha fractions such as C -C naphtha, heavy virgin naphtha, heavy coker naphtha, heavy steam cracked naphtha, heavy catalytic naphtha, etc. Particularly preferred feed stocks will include the light naphthas as described above, naphthas suitable as hydroformer feeds and naphtha products from the hydroforrning operation, which feeds will typically boil in the range of about 50 to 400F., preferably 80 to 350F. A prime hydroformer feed will have about a 180 to 360F. boiling range. A requirement for the feed stocks used in the present invention is that they contain a substantial quantity of straight chain hydrocarbons which are converted or removed in accordance with the present invention.

The above feed stocks are treated with the aforedescribed erionite catalysts in either fixed bed, moving bed, or fluidized solids operation, either upflow or downflow (in bed reactors), at the following operating conditions:

Naphthas of 200F boiling range *Naphthas in l80430F boiling range usable: in hydroforming Operations.

The essence of the present invention, namely the use of the aforedescribed catalysts for the selective removal of straight chain hydrocarbons can be utilized in various processing schemes depending upon the results desired. These various processing schemes will now be described in some detail as they represent specific embodiments of the present invention. 7

The catalysts of the invention can conveniently be used to upgrade naphtha fractions for inclusion in the high quality motor gasoline pools. This may involve a single stage operation wherein the naphtha feed is introduced into contact with the erionite catalyst at the aforedescribed conditions, and the resulting product has a greatly enhanced octane number.

The erionite catalyst of the invention can be utilized to upgrade previously hydrocracked feed stocks, e.g.

. an additional hydrocracking stage containing the erionite catalyst can be used in conjunction with a conventional hydrocracking operation in order to produce higher octane product. The conventional hydrocracking stages are conducted with any of the various available hydrocracking catalysts and most preferably with the newly developed relatively large pore (e.g. 6 to 15 angstrom units) crystalline aluminosilicate zeolite catalysts containing metallic hydrogenation components. Such catalysts have been extensively described in the recent prior art, e.g. US. Pat. Nos. 2,971,904 and 3,287,252. In this embodiment the total hydrocracked product from the relatively large pore size zeolite catalysts, or a selected portion thereof, may be contacted with the selective erionite catalyst of the invention. Intermediate fractionation and segregation of desired fractions can be used. Typical hydrocracking conditions with the large pore zeolite catalysts will include temperatures from about 400 to 800F., pressures of about 250 to 2500 psig, liquid hourly space velocities of about 0.2 to 2 v/v/hr and hydrogen rates of about 1000 to 20,000 scf/b.

The erionite catalysts of the invention can be used in conjunction with conventional hydroforming operations. In this case the erionite catalysts can be used either in a lead reactor to pretreat the feed passing to the hydroforming reactors, or can be utilized either in a separate tail reactor or in a bottom portion of the last hydroformer of the train, to selectively convert remaining straight chain hydrocarbons so as to further increase the octane number of the hydroformed product. The erionite catalyst can also be utilized in admixture with conventional hydroforrning catalysts in one or more conventional hydroforming reactors.

I claim:

1. An improved process for the shape selective conversion of straight-chain hydrocarbons from a hydrocarbon feed which comprises the selective conversion of said feed by contact, at elevated temperature and pressure and in the presence of hydrogen, with a catalyst comprising a crystalline aluminosilicate erionite, the erionite having no hydrogenation-dehydrogenation metal associated therewith and having been prepared by the steps of comprising (:1) exchange with the am monium cation, (b) exposing it to 100% steam at ele- 8 vated temperatures and (c) reexchanging with the ammonium cation.

2. The process of claim 1 wherein the zeolite following the first exchange is exposed to temperatures of from about 700F to about l400F.

3. The process of claim 1 wherein the zeolite following the exchange of step (c) is heated at from about 750F to about l100F.

4. The method of claim 1 wherein said erionite is natural erionite.

5. The method of claim 1 wherein said erionite is synthetic erionite.

6. The method of claim 1 wherein the exchanges are carried out at for from about 10 minutes to about 20 hours.

7. The method of claim 6 wherein the exchanges are carried out at a pressure of from 1 atmosphere to 3000 psig.

8. The method of claim 6 wherein the exchanges are carried out at from about F to about 680F.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 91 DATED 1 December 9', 1975 INVENTOR(S) I WILLIAM P. BURGESS It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 1, Formula "SiO yH O" should read SiO2 yH O.

Columns 5 & 6, Table 3, "E+o appearing below Table 3 a in Column 5 should appear after 0 "Calculated" in the table, 1 .e

-Calculated R+O(5)-.

Column 7,1ine 20, Delete the Word "of" before the word "comprising". Signed and gcalccl this Twentieth Day of July 1976 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (ummissioner vj'Parents and Trademarks 

1. AN IMPROVED PROCESS FOR THE SHAPE SELECTIVE CONVERSION OF STRAIGHT-CHAIN HYDROCARBONS FROM A HYDROCARBON FEED WHICH COMPRISES THE SELECTIVE CONVERSION OF SAID FEED BY CONTACT, AT ELEVATED TEMPERATURE AND PRESSURE AND IN THE PRESENCE OF HUDROGEN, WITH A CATALYST COMPRISING A CRYSTALLINE ALUMINOSILICATE ERIONITE, THE ERIONITE HAVING NO HYDROGENAKTION-DEHUDROGENATION METAL ASSOCIATED THEREWITH AND HAVING BEEN PREPARED BY THE STEPS OF COMPRISING (A) EXCHANGE WITH THE AMMONIUM CATION, (B) EXPOSING IT TO 100% STEAM AT ELEVATED TEMPERATURES AND (C) REEXCHANGING WITH THE AMMONIUM CATION.
 2. The process of claim 1 wherein the zeolite following the first exchange is exposed to temperatures of from about 700*F to about 1400*F.
 3. The process of claim 1 wherein the zeolite following the exchange of step (c) is heated at from about 750*F to about 1100*F.
 4. The method of claim 1 wherein said erionite is natural erionite.
 5. The method of claim 1 wherein said erionite is synthetic erionite.
 6. The method of claim 1 wherein the exchanges are carried out at for from about 10 minutes to about 20 hours.
 7. The method of claim 6 wherein the exchanges are carried out at a pressure of from 1 atmosphere to 3000 psig.
 8. The method of claim 6 wherein the exchanges are carried out at from about 75*F to about 680*F. 